//
// async_tcp_echo_server.cpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#include <cstdlib>
#include <iostream>
#include <memory>
#include <utility>
#include <boost/asio.hpp>

using boost::asio::ip::tcp;

class session
	: public std::enable_shared_from_this<session>
{
public:
	session(tcp::socket socket)
		: socket_(std::move(socket))
	{
	}

	void start()
	{
		do_read();
	}

private:
	void do_read()
	{
		auto self(shared_from_this());
		socket_.async_read_some(boost::asio::buffer(data_, max_length),
			[this, self](boost::system::error_code ec, std::size_t length)
		{
			if (!ec)
			{
				do_write(length);
			}
		});
	}

	void do_write(std::size_t length)
	{
		auto self(shared_from_this());
		boost::asio::async_write(socket_, boost::asio::buffer(data_, length),
			[this, self](boost::system::error_code ec, std::size_t /*length*/)
		{
			if (!ec)
			{
				do_read();
			}
		});
	}

	tcp::socket socket_;
	enum { max_length = 1024 };
	char data_[max_length];
};

class server
{
public:
	server(boost::asio::io_context& io_context, short port)
		: acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
	{
		do_accept();
	}

private:
	void do_accept()
	{
		acceptor_.async_accept(
			[this](boost::system::error_code ec, tcp::socket socket)
		{
			if (!ec)
			{
				std::make_shared<session>(std::move(socket))->start();
			}

			do_accept();
		});
	}

	tcp::acceptor acceptor_;
};

int main(int argc, char* argv[])
{
	try
	{
		if (argc != 2)
		{
			std::cerr << "Usage: async_tcp_echo_server <port>\n";
			return 1;
		}

		boost::asio::io_context io_context;

		server s(io_context, std::atoi(argv[1]));

		io_context.run();
	}
	catch (std::exception& e)
	{
		std::cerr << "Exception: " << e.what() << "\n";
	}

#ifdef _WIN32
	system("pause");
#endif
	return 0;
}
